6PE over CsC The SEEREN case

1. 6PE over CsC � The SEEREN case

3. Presentation Outline Introduction What is 6PE? - Basic characteristics Applicability Alternative solutions 6PE Implementation Details MPLS VPN - 6PE innovation Configuration Overview - Label Distribution Packet Forwarding The SEEREN Case The network What is CsC? � 6PE over CsS Configuration - Troubleshooting Conclusions

4. What is 6PE? A method that allows an MPLS-based ISP to offer IPv6 interconnection services to his/her customers without upgrading the entire network to support IPv6 protocols.

5. Basic characteristics 6PE is similar to MPLS VPNs model in terms of technical implementation and complexity. Label encapsulation is used for transporting IPv6 packets. IPv6 functionality is enabled only at the edge routers. A 6PE router, in simple terms, is an edge router with IPv6 functionality. Core routers are IPv6 unaware, a.k.a. support IPv4 only protocols.

6. Applicability 6PE is deployed by ISPs that have MPLS core networks and (possible) offers MPLS VPN (or other) services. IPv6 services are requested by a small number of customers. If the IPv6 customers are limited, an L2 tunnelled solution may be preferable. If the IPv6 customers require most of the (access) edge routers to be upgraded, ISP may consider to upgrade to whole network. The ISP wants to avoid either to fully upgrade the core network or to deploy L2/L3 tunnels. Why?

7. Alternative Solutions Dual stack network IPv6 and IPv4 traffic is treated identically by the core routers. ? Requires IPv4/IPv6 routing and label distribution protocols. ? L2 MPLS VPNs Use MPLS to create point-to-point tunnels that terminate at the edge routers. IPv6 is needed only at edge routers. No changes are needed to core routers. ? Scalability problems arise in heavily (L2 tunnel) mesh topologies. ? Edge routers has to support the appropriate functionality, e.g. ATOM or CCC/TCC. ?

8. Presentation Outline Introduction What is 6PE? - Basic characteristics Applicability Alternative solutions 6PE Implementation Details MPLS VPN - 6PE innovation Configuration Overview - Label Distribution Packet Forwarding The SEEREN Case What is CsC? � 6PE over CsS Configuration - Troubleshooting Conclusions

9. MPLS VPNs Simplified Terminology CE: Customer Edge Router (C1,C2) PE: Provider Edge Router (Ra, Rd) P: Provider Core Router (Rb, Rc) Packet Forwarding based on two labels imposed at the ingress point of the MPLS network Label Distribution for IGP routes Routers in the MPLS domain create labels for all the known IPv4 IGP routes. Label information is exchanged with a Label Distribution Protocol, e.g. LDP or BGP. Labels + Routing Table ? Label Forwarding Information Base (LFIB) Label Distribution for VPNs MP-BGP is used for VPN information exchange VPN Routes + VPN Label for each PE Packet Forwarding Ingress VPN interface: On packet arrival lookup the VPN table and find (a) the label for the VPN route and (b) the egress router Push two labels; Inner label for the VPN route and Outer label towards the egress router

10. 6PE �innovation� Provided that routers Ra, Rd, C1, and C2 are dual stack could the MPLS VPN technique be used for forwarding IPv6 traffic from C1 to C2? Why not? One label could be used for frame forwarding through the MPLS (IPv4) network while the other label could be used for identifying the IPv6 route. There are some problems, though! How Rd will find the egress router Ra? Not with IPv4 IGPs (cannot carry IPv6) Not with IPv6 IGPs (are not supported by the core) Solution? MP-BPG How will Rd determine the inner label? Solution ? MP-BGP again

11. Configuration Overview Step 1: Upgrade PEs to become Dual Stack Step2: Populate the PE�s IPv6 Routing Table Establish IPv6 route exchange with the CE Step3: Establish MP-BGP Exchange IPv6 Routes Exchange IPv6 Labels

12. Step 1: Upgrade PEs to Dual Stack Upgrade to an IOS that supports 6PE: IPv6 BGP-MP Enable IPv6 Optionally, assign IPv6 addresses to some interfaces

13. Step 2: Built the v6 routing table PE router is dual stack IPv6 routing table exists IPv6 routing table can be populated with: Routes learned through eBGP between CE and PE (typically) Routes of connected interfaces Routes learned through an IPv6 capable IGP protocol (e.g. ISIS) Static or default routes ? These routes (IPv6 Table) need to be exchanged with the other PEs

14. Step 2: Configuration Commands

15. Step 3: Establish MP-BGP Exchange IPv6 Routes 6PE routers establish MP-BGP sessions running over IPv4 BGP Next Hop field is the IPv4-mapped IPv6 address of the 6PE router Mapping: X.Y.Z.W ? ::FFFF:X.Y.Z.W IPv6 prefixes are exchanged Exchange Labels An �Aggregated IPv6 Label� is sent for IPv6 routes. This will be used as the �inner� label

16. Step 3: Configuration Commands include �sent-label� in the ipv6 address family Must be done in both directions PEs In a Mesh of PEs, it must be done with all PEs

17. Packet Forwarding in 6PE On packet arrival at the ingress 6PE: The IPv4-mapped IPv6 BGP next-hop for the destination address is found Two labels are pushed: Inner label: The label for the BGP next-hop Outer label: The label for the IPv4 address correspinding to the IPv4-mapped IPv6 address Forwarding: Swap exterior label Penultimate Hop Popping (PHP) Last Hop: Packet received with interior label only Inner label ? VPN & egress interface The last label is popped, the IP packet is forwarded to the CE router

18. Presentation Outline Introduction What is 6PE? - Basic characteristics Applicability Alternative solutions 6PE Implementation Details MPLS VPN - 6PE innovation Configuration Overview - Label Distribution Packet Forwarding The SEEREN Case The network What is CsC? � 6PE over CsS Configuration - Troubleshooting Conclusions

19. Case Study: The network SEEREN: South Eastern European Research & Educational Network Upstream: GRNET (Greek Research Network) Backup Upstream: Roedunet (via GRNET) Peers: Serbia & Montoragevo, Bulgaria, Albania, FYROM, Bosnia & Herzecovinova Connectivity: Oteglobe, via a CSC MPLS VPN

20. What is CsC? Carrier-Supporting-Carrier Designed for ISPs that are VPN customers of other (larger MPLS) ISP. A VPN with very small virtual routing table (VRF) MPLS between CsC-CE and CsC-PE CsC-CEs exchange limited labels with CsC-PE

21. 6PE over CsC Integration of two techniques 6PE functionality is installed on the CEs instead of the PEs! 6PE peers belong to different administrative domains. Three Label Stack !!! Feasible, because CE-PE connection uses MPLS.

22. SEEREN 6PE Configuration #1 hostname athens-2 ! ipv6 unicast-routing ipv6 cef ! interface Loopback0 ip address 194.177.210.40 255.255.255.255 ! interface ATM1/0/0.1 point-to-point description SEEREN via OteGlobe VPN ip address 62.75.33.246 255.255.255.252 ! interface GigabitEthernet3/0/0 description Athens2 - Athens3 ipv6 address 2001:648:2FFF:106::2/126 ipv6 router isis ! router isis � �

23. SEEREN 6PE Configuration #2

24. 6PE verification & troubleshooting

25. 6PE verification & troubleshooting

26. Presentation Outline Introduction What is 6PE? - Basic characteristics Applicability Alternative solutions 6PE Implementation Details MPLS VPN - 6PE innovation Configuration Overview - Label Distribution Packet Forwarding The SEEREN Case The network What is CsC? � 6PE over CsS Configuration - Troubleshooting Conclusions

27. Conclusions 6PE is applicable only if there is an MPLS core network and limited number of customers asks for IPv6 services. Otherwise, consider other solutions. Avoid changing the (IPv4) MPLS core network, a.k.a. minimal operational cost and risk 6PE is similar to MPLS VPNs technique in terms of technical implementation and complexity. Scalability properties Requirements: CE is dual stack and exchange IPv6 routing information with local PE router. P and PE routers support MPLS and IPv4 IGP! PE routers support also MP-BGP and 6PE functionality

28. Acknowledgements

29. Questions? Thank You!